1. Field of the Invention
The present invention relates to a technology for testing the operation of a semiconductor integrated circuit or a display device, that is, a probing technology, and in particular, to a member for the purpose of removing foreign matter adhering to the tip of a probe which is put into contact with a pad for testing the operation of the semiconductor integrated circuit or the display device, for example, metals, metal oxides, and contaminants inhibiting electric contact, a method of manufacturing the removing member, a method of cleaning foreign matter adhering to the probe tip by the use of the removing member, a probe cleaned by the removing member, and a probing apparatus to which the removing member is applied.
2. Description of the Related Art
For example, the probe of a probe card, which serves as an interface for electric signals transferred between a probing apparatus for measuring electric characteristics of a semiconductor integrated circuit formed on a semiconductor wafer (hereinafter referred to as a semiconductor chip) and the semiconductor chip, is forcibly put into contact with the bonding pads which are made of aluminum alloy and formed on the semiconductor chip to scratch the pads. For this reason, aluminum and aluminum oxide scratched from the pad material or contaminants remaining on the surfaces of the bonding pads adhere to the probe tip. If the adhering foreign matters are not removed from the probe tip, the electric resistance (contact resistance) between the probe and boding pads is so increased that the electrical characteristics of the semiconductor chip can not be accurately measured. Further, when the probe is used for a long time with the adhering foreign matters kept deposited on the probe tip, the electric resistance increases as time elapses. As a countermeasure against this phenomenon, conventionally, the probe tip is cleaned at intervals of predetermined times of probing to remove the adhering foreign matters.
For example, Japanese Patent Laid-open No. Hei. 7-244074 discloses an abrasive sheet formed by mixing fine-grained abrasives for grinding in an elastic matrix and then shaping the matrix into a sheet, an abrasive sheet, that is, a cleaning sheet. The cleaning sheet is attached, instead of a semiconductor wafer, onto a wafer moving table of a probing apparatus which is operated to put a semiconductor wafer into contact with a probe card. The wafer moving table is vertically moved to press the tip of the probe against the surface of the cleaning sheet to produce contact friction between the tip face of the probe and the abrasive grains dispersed in the cleaning sheet to thereby remove the foreign matter adhering to the probe tip.
Further, Japanese Patent Laid-Open No. Hei. 11-97496 already published as an invention made by the inventors of the present invention discloses a technology of removing, foreign matter adhering to the probe tip by the use of a cleaning sheet formed by applying a metallic thin coating film having a high tensile strength to the surface of a resin material and then forming a ceramic layer or an abrasive layer with abrasive grains fixed thereto on the surface of the metallic thin film.
Still further, for example, Japanese Patent Laid-open No. Hei. 11-345846 or Japanese Patent Laid-Open No. Hei. 10-300777 discloses a technology of removing foreign matter adhering to the probe tip by use of a cleaning sheet formed by forming a thin film for cleaning on an elastic sheet.
A conventional cleaning sheet for removing foreign matters adhering to the probe tip is formed, for example, by mixing fine-grained abrasives into an elastic matrix, as described above. When the tip of the,probe is pressed on the surface of the cleaning sheet formed in this manner, the cleaning sheet is deformed and, as shown in FIG. 9, the tip of the probe 1 is pressed into the matrix 102 to present the following problem: the fine-grained abrasives 103 grind the probe 1 in a predetermined region to shave and thin the probe tip while repeating cleaning, finally bending or braking the probe 1 itself because the strength of the probe 1 becomes insufficient.
Further, the research carried out by the present inventors has revealed recently that, from the viewpoint of the contact of the probe tip and the semiconductor electrode pad, the probe tip formed in the shape of a nearly spherical surface having a predetermined diameter R deeply related to the thickness of a pad electrode material with which the probe is put into contact or a nearly spherical surface having a flat portion at a portion (hereinafter collectively referred to as a nearly spherical surface) is most suitable. In the case where the probe with a tip formed in such a shape is used for a cleaning method using a conventional cleaning sheet, the probe tip formed in the shape of a nearly spherical surface is shaved and deformed by the cleaning action, resulting in a problem of degrading the electrical contact of the probe.
For this reason, in order to solve the above problems, the present inventors invented a cleaning sheet capable of cleaning the adhering foreign matter while it was deformed along the shape of the probe tip, that is, a removing member, and disclosed the contents of the invention in Japanese Patent Laid-Open No. Hei. 11-97496. However, there was room for improvement as to the raising of dust by the separation or the fallout of abrasives in a ceramic coating abrasive layer or an abrasive grain of abrasive layer formed on the surface of the cleaning sheet.
Further, Japanese Patent Laid-Open No. Hei. 10-300777 or Japanese Patent Laid-Open No. Hei. 1-345846 discloses a technology relating to a cleaning sheet for accomplishing an object similar to the object of the related art, that is, an object of preventing the probe tip from being shaved and deformed when cleaned, but there have been left some problems to be described below for the cleaning sheet to be deformed along the shape of the probe tip and at the same time to exert a grinding function.
In practice, when the probe tip is cleaned by using the cleaning sheet manufactured based on the invention disclosed in the above patent gazette and commercially sold, the cleaning sheet presents a problem that the probe tip plastically deforms and damages the surface of the cleaning sheet to deeply scratch an abrasive grain layer to shorten the life of the cleaning sheet because of the insufficient flexibility of the cleaning sheet, that is, because of high deflection rigidity of the cleaning sheet. Further, there are left some other problems when the cleaning sheet is put into practice, such as difficulty in cleaning the complete region of the probe tip where the foreign matters are attached.
Further, in order to effectively grind the probe tip and to elongate the grinding life of the cleaning sheet, it is necessary to smoothly slide the probe tip in contact with the surface of the cleaning sheet and hence it is indispensable to improve the performance of the cleaning sheet for the purpose of realizing an ideal cleaning sheet capable of keeping the good shape of the probe tip.
Still further, as the trend has been in recent years for semiconductor electrode pads to narrow pitches and to increase the number of pins, it is expected that a probe called a membrane probe will be frequently employed in the near future in which projecting portions of electrodes are arranged in a plane without using wire material as is the case with a conventional probe card. However, there is a problem that the cleaning sheet used by the method of sticking the probe tips in the cleaning sheet can not be used for cleaning the projecting portions of such a membrane probe. Also a probe card of a vertical probe type in which wires are vertically disposed to increase the density of wire arrangement has the same problem, namely, that the cleaning sheet used by the method of sticking the probe tips in the cleaning sheet can not be used. These problems have been an obstacle for a high density probe card to come into widespread use.
The present invention has been made to solve the above problems. The object of the present invention is to provide a member for removing foreign matters adhering to a probe tip which can elongate the life of the probe by removing the foreign matters adhering to the probe tip while preventing the probe tip from being shaved and made slender and keeping the shape of the probe tip, a method of manufacturing the removing member, a method of effectively cleaning the probe by the use of the removing member, a probe cleaned by the removing member, and a probing apparatus to which the removing member is applied.
A member for removing foreign matters adhering to a probe tip in accordance with the present invention includes: a base plate; a first elastic member formed on the base plate; a second elastic member formed on the first elastic member; and an abrasive layer which is made of hard particles and a binding material and is formed on the second elastic member. Therefore, it is possible to effectively clean the foreign matters adhering to the probe tip while keeping the shape of the probe tip by using such a removing member to clean the probe.
Further, a method of manufacturing a member for removing foreign matters adhering to a probe tip in accordance with the present invention includes the steps of: forming a first elastic member on a base plate; forming a second elastic member on the first elastic member; and forming an abrasive layer made of hard particles and a binding""material on the second elastic member. Therefore, it is possible to manufacture the member for effectively removing the foreign matters adhering to the probe tip while keeping the shape of the probe tip.
Still further, a method of cleaning foreign matters adhering to a probe tip in accordance with the present invention is characterized in that a probe whose tip is shaped like a nearly spherical surface or a nearly spherical surface having a flat portion at a portion is slid on the above-mentioned removing member placed on a wafer stage in such a way as to draw a closed loop path to thereby remove the foreign matters adhering to the probe tip. Therefore, it is possible to effectively clean the foreign matters adhering to the probe tip while keeping the shape of the probe tip.
Still further, a probe in accordance with the present invention has a tip shaped like a nearly spherical surface or a nearly spherical surface having a flat portion at a portion and can remove the foreign matters adhering to the probe tip by the above-described cleaning method. Therefore, by employing the present probe, it is possible to keep a contact resistance small when a measurement is made.
Still further, a probing apparatus in accordance with the present invention includes: a probe whose tip is shaped like a nearly spherical surface or a nearly spherical surface having a flat portion at a portion; the above-described member for removing the foreign matters adhering to the probe tip; and a wafer stage which can move in a horizontal direction and in a vertical direction in such a way as to slide the probe on the removing member placed thereon along a closed loop path. Therefore, it is possible to effectively easily clean the foreign matters adhering to the probe tip while keeping the shape of the probe tip which is a part of the probing apparatus.
Other objects and attainments together with a fuller understanding of the invention will become, apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.